From 22ea5995540a65746981d464b5419973b4699ad4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sybren=20A=2E=20St=C3=BCvel?= <sybren@blender.org>
Date: Thu, 17 Mar 2022 11:03:29 +0100
Subject: [PATCH] Manager: periodically run the SQL `VACUUM` command

---
 cmd/flamenco-manager/main.go       |  2 ++
 internal/manager/persistence/db.go | 27 +++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/cmd/flamenco-manager/main.go b/cmd/flamenco-manager/main.go
index 15be6c3e..f3768000 100644
--- a/cmd/flamenco-manager/main.go
+++ b/cmd/flamenco-manager/main.go
@@ -75,6 +75,8 @@ func main() {
 
 	// Construct the services.
 	persist := openDB(*configService)
+	go persist.PeriodicMaintenanceLoop(mainCtx)
+
 	flamenco := buildFlamencoAPI(configService, persist)
 	e := buildWebService(flamenco, persist, ssdp)
 
diff --git a/internal/manager/persistence/db.go b/internal/manager/persistence/db.go
index 3e76486e..68bc680e 100644
--- a/internal/manager/persistence/db.go
+++ b/internal/manager/persistence/db.go
@@ -5,6 +5,7 @@ package persistence
 
 import (
 	"context"
+	"time"
 
 	"github.com/rs/zerolog/log"
 	"gorm.io/gorm"
@@ -13,6 +14,8 @@ import (
 	"github.com/glebarez/sqlite"
 )
 
+const vacuumPeriod = 1 * time.Hour
+
 // DB provides the database interface.
 type DB struct {
 	gormDB *gorm.DB
@@ -57,3 +60,27 @@ func openDBWithConfig(uri string, config *gorm.Config) (*DB, error) {
 	}
 	return &db, nil
 }
+
+// PeriodicMaintenanceLoop periodically vacuums the database.
+// This function only returns when the context is done.
+func (db *DB) PeriodicMaintenanceLoop(ctx context.Context) {
+	log.Debug().Msg("periodic database maintenance loop starting")
+	defer log.Debug().Msg("periodic database maintenance loop stopping")
+
+	var waitTime time.Duration
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-time.After(waitTime):
+			waitTime = vacuumPeriod
+		}
+
+		log.Debug().Msg("vacuuming database")
+		tx := db.gormDB.Exec("vacuum")
+		if tx.Error != nil {
+			log.Error().Err(tx.Error).Msg("error vacuuming database")
+		}
+	}
+}